Laser scanning technology (LiDAR) empowers API inspectors and engineers to rapidly perform comprehensive and detailed analysis of storage tanks, allowing decision makers to act quickly and confidently. LiDAR operates like radar technology but uses light rather than radio waves. An emitter sends a laser pulse that will impinge on a surface and cause the light pulse to be reflected. The reflected pulse then returns to a receiver, measuring the time required for emission and return. The time of flight and speed of light are then used to determine the distance of each data point from the source. This methodology allows for the rapid collection of physical tank data.
Unlike traditional inspection techniques, LiDAR can capture the entire tank structure in detail within the span of a few hours, minimizing scheduled downtime and exposure of personnel to potentially toxic environments. The unprecedented measurement coverage provides high-resolution point-cloud data to the user and enables further analysis to be conducted without the need to return to the site. Scans can be captured safely from the ground without interfering with on-site activities.
New technologies in data registration eliminate the need to place targets in-field, reducing training, on-site preparation and risk of project failure. This enables local teams to perform scanning, which reduces mobilization costs and turnaround time. Reduced turnaround time means that tanks are out of service for shorter intervals, saving the user time and resources.
Advanced algorithms are used to evaluate as-built conditions by reconstructing the tank in 3-D with survey-grade accuracy from hundreds of millions of data points. Improvements in computing power allows this to be completed in a matter of a few hours once scanning is completed.
Accurate 3-D models are used to identify deformations of each component from design dimensions. These analyses include floor settlement, shell deflection, shell peaking and banding, shell verticality, column verticality, girder and rafter deflection, roof settlement and floating- roof rim space. Holistic analysis of the tank allows inspectors to trace the root cause of a failure. The graphic user interface (GUI) will highlight areas of localized stress, making it simple to identify areas of risk and address those concerns. If a problem area is identified, engineers can easily isolate and extract data to perform additional investigations.
Further, LiDAR technology is being adopted as a standa rd practice at several tank facilities and may eventually become the status quo with regard to tank inspection services. Companies that can perform and interpret LiDAR data are ahead of the growing trend and may be more prepared for the future of tank inspections.
Other applications for LiDAR are secondary containment sufficiency analyses. Flow modeling is applied to determine the volumetric capacity, freeboard volume, overflow location and direction of overflow for these structures. LiDAR is also used for tank calibration. Detailed models of the internal structure of the tank allow for accurate deadwood delineation, especially in complex tanks equipped with heating coils.
A 3-D model showing the point cloud with roof, floor and shell deformation analysis.
For more information, contact Josiah Lau at jlau@novlum.com or visit www.novlum.com/trs.